.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.TH PTHREAD_ATTR_SETSCHEDPARAM 3 2021-03-22 "Linux" "Linux Programmer's Manual"
.SH NAME
pthread_attr_setschedparam, pthread_attr_getschedparam \- set/get
scheduling parameter attributes in thread attributes object
.SH SYNOPSIS
.nf
.B #include <pthread.h>
.PP
.BI "int pthread_attr_setschedparam(pthread_attr_t *restrict " attr ,
.BI "                              const struct sched_param *restrict " param );
.BI "int pthread_attr_getschedparam(const pthread_attr_t *restrict " attr ,
.BI "                              struct sched_param *restrict " param );
.PP
Compile and link with \fI\-pthread\fP.
.fi
.SH DESCRIPTION
The
.BR pthread_attr_setschedparam ()
function sets the scheduling parameter attributes of the
thread attributes object referred to by
.IR attr
to the values specified in the buffer pointed to by
.IR param .
These attributes determine the scheduling parameters of
a thread created using the thread attributes object
.IR attr .
.PP
The
.BR pthread_attr_getschedparam ()
returns the scheduling parameter attributes of the thread attributes object
.IR attr
in the buffer pointed to by
.IR param .
.PP
Scheduling parameters are maintained in the following structure:
.PP
.in +4n
.EX
struct sched_param {
    int sched_priority;     /* Scheduling priority */
};
.EE
.in
.PP
As can be seen, only one scheduling parameter is supported.
For details of the permitted ranges for scheduling priorities
in each scheduling policy, see
.BR sched (7).
.PP
In order for the parameter setting made by
.BR pthread_attr_setschedparam ()
to have effect when calling
.BR pthread_create (3),
the caller must use
.BR pthread_attr_setinheritsched (3)
to set the inherit-scheduler attribute of the attributes object
.I attr
to
.BR PTHREAD_EXPLICIT_SCHED .
.SH RETURN VALUE
On success, these functions return 0;
on error, they return a nonzero error number.
.SH ERRORS
.BR pthread_attr_setschedparam ()
can fail with the following error:
.TP
.B EINVAL
The priority specified in
.I param
does not make sense for the current scheduling policy of
.IR attr .
.PP
POSIX.1 also documents an
.B ENOTSUP
error for
.BR pthread_attr_setschedparam ().
This value is never returned on Linux
(but portable and future-proof applications should nevertheless
handle this error return value).
.\" .SH VERSIONS
.\" Available since glibc 2.0.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR pthread_attr_setschedparam (),
.BR pthread_attr_getschedparam ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH CONFORMING TO
POSIX.1-2001, POSIX.1-2008.
.SH NOTES
See
.BR pthread_attr_setschedpolicy (3)
for a list of the thread scheduling policies supported on Linux.
.SH EXAMPLES
See
.BR pthread_setschedparam (3).
.SH SEE ALSO
.ad l
.nh
.BR sched_get_priority_min (2),
.BR pthread_attr_init (3),
.BR pthread_attr_setinheritsched (3),
.BR pthread_attr_setschedpolicy (3),
.BR pthread_create (3),
.BR pthread_setschedparam (3),
.BR pthread_setschedprio (3),
.BR pthreads (7),
.BR sched (7)
.SH COLOPHON
This page is part of release 5.13 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.
